In a gravity type of railroad marshalling or classification yard, it is conventional practice to employ grip or squeeze types of car retarders at both master and group locations to control the leaving speeds of humped railway cars or vehicles. Additionally, it is also becoming increasingly common to employ a car retarder at the exit end of each of the class tracks in the yard to stop the oncoming railway cars as they are processed into the respective classification tracks. The car retarders frictionally engage or grip the opposite sides of the car wheels to slow down the moving railway cars as they pass through the master and group locations and to arrest the railway vehicles in the class tracks. On numerous occasions, the frictional gripping action between the brake shoes and wheel results in extremely loud and piercing squealing noises to permeate the immediate area surrounding or bordering the classification yard. These high pitched screeching sounds not only are irritating or annoying to the people in the surrounding area but also are painful and injurious to working personnel in the classification yard. In some cases, a partial or total loss of hearing may result when employees are exposed to the retarder noises for extended periods of time. It has been found that long-term exposure to sounds above a given critical level adversely affects workmen or supervisory personnel who work in the area of the car retarders. These acute and detrimental sound waves are produced by the stick-slip or rubbing action which takes place between the sides of the wheels of the moving car and the engaging surfaces of the brake shoes of the actuated car retarder. In actual operation, it has been found that the most troublesome pitch or frequency range of the retarder generated sound waves lies between 2,000 to 4,000 hertz. Further, the loudness or amplitude level of the noises may reach 130 decibels (db) or on the H scale more at a distance of 8 feet or less from the car retarder. Otolarynologists, audiologists and other qualified specialists have found that human beings experience discomfort and pain when exposed to noise level of 120 db or more and that repeated exposure to such high levels of noise can eventually result in hearing losses. Recently there have been numerous proposals and attempts to eliminate or at least reduce the noise level in order to comply with the regulations of the Occupational Safety and Hazard Act and the noise pollution ordinances of the given locale. However, each of these previous attempts was either prohibitively expensive or mechanically unsound and, therefore, did not meet with industry-wide acceptance. The proposition of replacing steel brake shoes with ductile iron appeared plausible but proved uneconomical since ductile iron shoes wear four times as fast as steel. Hence, a railroad car retarder equipped with ductile iron shoes normally requires four times as many shoe replacements as an all-steel retarder. Obviously, a car retarder fitted with ductile iron shoes needs a greater number of adjustments and requires more periods of maintenance than a car retarder equipped with steel shoes. The use of lubricants, such as, oils and mixtures of other unctuous liquids, that are sprayed or otherwise applied to the contacting surfaces of the brake shoes and wheels for eliminating wheel squealing or screeching noises is also possessed of several shortcomings. The utilization of lubricants not only materially decreases the effective braking length of the car retarder but also dramatically increases the initial purchase price as well as the subsequent maintenance cost of the overall car retarder. A further deleterious effect of employing lubricants in combating the noise pollution problem is the unctuous ground covering in the immediate area of the car retarder as well as the oil dropping pollution caused throughout the classification yard. A further method in attempting to resolve the noise pollution problem in classification yards has been the erection of sound barriers or walls on the respective sides of the railroad car retarder. In previous types of noise barriers, the use of porous noise absorption material was unacceptable in that they soon become relatively ineffective in suppressing the noise produced by the car retarder. The principal reason for the loss in sound attenuation resides in the fact that the porous material readily becomes clogged with foreign matter, such as, dirt, oil, grease, water, ice and the like, which is common in a classification yard environment. In addition, low density types of noise absorption materials are generally susceptible to rapid deterioration due to the adverse physical and climatic conditions which are present in railroad yard milieu. Further, it will be appreciated that the maximum theoretical value of noise reduction or attenuation provided by a barrier structure is approximately 25 db which in many cases is insufficient to conform with the noise abatement ordinances in the particular locale and the safety standards set forth in the Occupational Safety Hazard Act of 1970. In present classification yards and in future proposed yard locations, it has been found that even at substantial distances, 5,000 feet or more, the noise level that permeates the area beyond the boundary line of the yard is in excess of the maximum permissible amplitude set forth in many of the local noise abatement ordinances. Thus, there is a vital need for providing an efficient noise reduction arrangement for effectively reducing or eliminating wheel squealing or screeching sounds produced by railroad car retarders. In addition, there are numerous other places or locations in railroad or steel-wheel-on-steel-rail mass and/or rapid transit operations where wheel squealing noises are produced by the interaction of the wheels of the moving vehicles and the running rails. For example, when vehicles traverse curved track sections, the wheels have a tendency to become skewed so that binding and abrading action occurs which results in the generation of squealing sounds. Likewise, there are sections of track that have tight gage portions which cause the production of wheel squealing noises. That is, when the distance between the two rails of the track become less than the normal or standard gage the inside surface portions of the rails seize the flanges of the vehicle wheels so the vibrational forces are imparted to the wheels which result in wheel screeching noises. These wheel squealing sounds are somewhat irritating to operating personnel and passengers onboard the vehicles and are offensive to wayside commuters as well as to the workers and inhabitants in the immediate area of the trackway. Thus, like in classification or marshalling yards, there are municipal ordinance and governmental requirements which make it incumbent upon the railroad companies and mass and/or rapid transit authorities to suppress and eliminate noise pollution in the operation of their systems.